Rotary piston machine



Oct. 24, 1967 J. ASSUM 3,348,529

' ROTARY PISTON MACHINE Filed Aug. 10, 1965 4 Sheets-Sheet 1 INVENTOR1967 Y J ASSUM 3,348,529

ROTARY PISTON MACHINE Filed Aug. 10, 1965 4 Sheets$heet 2 F/G. 6 I

INVENTOR.

' W #wum' BY Oct. 24, 1967 J, ASSUM 3,348,529

ROTARY PI STON MACHINE Filed Aug; 10, 1965 Y '4 Sheets-$heet a INVENTOR.

Maize/ Oct. 24, 1967 J. AssuM ROTARY PISTON MACHINE 4 Sheets-Sheet 4Filed Aug. 10, 1965 INVENTOR.

United States Patent 3,348,529 ROTARY PISTON MACHINE Johann Assum,Augsburg, Germany, assignor to Messerschmitt Aktiengesellschaft,Augsburg, Germany Filed Aug. 10, 1965, Ser. No. 478,654 14 Claims. (Cl.123-8) ABSTRACT OF THE DISCLOSURE A rotary piston machine fortransmitting torque between a piston performing a composite rotarymotion and a shaft consisting of a casing; a rotor in this casing androtary means which are mounted in the casing for rotation about an axisand which include a shaft and a flange of this shaft. The rotary machinealso includes a plurality of crank shafts mounted on said flange and onthe rotor, respectively, for turning movement so as to transmit a torquebetween the rotor and the rotary means.

The present invention rel-ates to a rotary piston machine, and moreparticularly to apparatus for transmitting a torque between a pistonperforming a composite rotary motion and a shaft.

Rotary piston machines are known, for example combustion engines, inwhich a rotary piston having three peripheral corners is guided along aninner annular guide face of a casing. Since the guide face is anon-circular, and preferably of epitrochoid configuration, the pistonperforms a composite motion which has to be transferred to an outputshaft rotating about its axis. In accordance with the prior art, thetransmission of the torque of the rotary piston to the output shaft iseffected by an inner gear of the rotary piston meshing with a spur gearsecured to the output shaft. In a known machine of this type, the ratioof the teeth of the two gears is 352.

It is a disadvantage of this known construction that only a few teeth ofthe gears are in positive meshing engagement. Furthermore, it isditficult to control the relative motion between the gears. In the eventthat play develops, the rotary piston flutters or vibrates, which causesimpacts of the guide portions of the rotary piston on the guide face ofthe casing, resulting in damage to the guide face, and great wear,causing increased vibrations and more play. The rotary speed of theshaft is three times the rotary speed of the rotary piston. Since rotarypiston engines operate at a substantially higher rotary speed than thecrank shaft of conventional engines with reciprocating pistons, theresulting high rotary speed of the output shaft is undesired. In orderto reduce the high rotary speed of the shaft to a practical rotaryspeed, a reduction gearing is required by which the efliciency and theoutput torque of the machine is produced. Another disadvantage of theknown construction is that the gradually developing play between themeshing gear teeth cannot be compensated by adjustment of the gears.

It is one object of the invention to overcome the disadvantages of knownrotary piston machines, and to provide means for supporting the rotarypiston on a plurality of movable means so that the forces produced bycombustion gases and by the mass of the rotary piston, are moreuniformly distributed, and a precise and uniform composite motion of therotary piston is assured.

Another object of the invention is to provide a transmission between therotary piston and a shaft which permits substantially the same rotaryspeed of the shaft and of the rotary piston.

Another object of the invention is to connect the rotary piston with ashaft by a transmission including gears permitted an adjustment tocompensate for play between the gear teeth.

Another object of the invention is to support the rotary piston on aflange of a drive shaft or driven shaft in such a manner that relativemotions between the piston and the shaft caused by the composite motionof the piston are possible.

With these objects in view, the present invention is concerned with animprovement of :a rotary piston machine, particularly of the type inwhich a multi-cornered piston performs a composite motion along anon-circular annular guide face of a casing.

One embodiment of the invention comprises a rotor including a rotarypiston means performing a composite rotary motion in a casing means;rotary means preferably including a shaft and a flange mounted in thecasing means for rotation about an axis; and a plurality of eccentricmeans angularly spaced about said axis and being respectively mounted inthe flange of the rotary means and in the rotor for turning movementabout parallel axes. In this manner, a torque is transmitted between therotor and the shaft.

Each eccentric means includes a pinion which meshes with a gear mountedon the casing means coaxial with the axis of the shaft.

In one embodiment of the invention, each eccentric means includes acircular plate turnably mounted in the rotor, either directly on therotary piston means or on a member fixedly connected with the same, ashaft portion mounted in the flange of the shaft, and a support portionto which the pinion is secured.

In another embodiment, a crank shaft has a first journal portion mountedin the rotor, and a second journal portion mounted in the flange of theshaft.

It is possible to mount the flange of the shaft and the stationary gearin recesses of the rotary piston, and to provide central openings in therotary piston and in the stationary gear through which the shaft passes.In an other embodiment of the invention, the rotor includes in additionto the rotary piston which is mounted in a separate casing, a rotarymember in which angularly spaced bores receiving the circular members ofthe eccentric means are provided. In this embodiment, a separate casinghouses the output shaft and its flange, the stationary gear, and theabove-mentioned member which forms part of the rotor. In one embodimentof the invention, the stationary gear and the flange are located in therecess of the rotary piston, and the shaft passes through centralopenings in the piston and in the stationary gear.

In all embodiments of the invention, it is preferred to mount thestationary gear on the casing means adjustable in relation to thepinions so that play may be taken up by adjustments.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings, inwhich:

FIG. 1 is an elevation with a cover plate removed, and partially insection along line 11 in FIG. 2;

FIG. 2 is an axial sectional view taken on line 22 in FIG. 1;

FIG. 3 is an enlarged view of a detail as viewed in the direction of thearrow A in FIG. 2; t

FIG. 4 is an axial sectional view taken on line 4-4 in FIG. 6;

FIG. 5 is a fragmentary view on an enlarged scale taken in the directionof the arrow A in FIG. 4 and illustrating a detail;

FIG. 6 is an elevation with one cover plate of the casing removed, andpartially in section along line C-D in FIG. 4;

FIG. 7 is an elevation with another cover plate removed, and partiallyin section on line A-B in FIG. 4, FIG. 5 to 7 illustrating a secondembodiment of the invention;

FIG. 8 is an axial sectional view taken on line 88 in FIG.

FIG. 9 is a fragmentary view on an enlarged scale taken in the directionof the arrow A in FIG. 8, and illustrating a detail;

FIG. 10' is a side elevation, partially in section along line 1010 inFIG. 8, FIGS. 8 to 10' illustrating a third embodiment of the invention;

FIG. 11 is a fragmentary sectional view taken on line 11-11 in FIG. 12;and

FIG. 12 is a side elevation of the structure shown in FIG. 11, FIGS. 11and 12 illustrating a modification of the embodiments of FIGS. 1, 4, and8.

Referring now to the drawings, corresponding parts are designated bylike reference numerals. In the embodiment of FIG. 1, casing means areprovided which include an annular body 4 provided with inlet and outletmeans 4a, 4b and having an inner annular guide face of epitrochoidconfiguration. The sides of the annular casing portion 4 are closed bycover plates 3 and 11 which are secured by screws to the central casingportion 4. Cover plate 11 has a central bore in which a ball bearing 5is mounted.

Cover plate 3 has a larger central bore in which a hub portion of a spurgear 12 is turnably mounted. The hub portion of gear 12 has a largerflange provided with partcircular slots 13 through which screws 14 passinto threaded bores of cover plate 3, as best seen in FIG. 3. Gear 12has a central opening at the end of which a hearing 5a is provided forsupporting shaft 1 which is also supported in bearing 5. Shaft 1 has astar-shaped flange 2 located adjacent gear 12 in a recess 9a of a rotarypiston 9 which has three corners, and arcuate surfaces between thecorners. Guide portions at the corners of rotary piston 9 slide alongthe inner epitrochoid face of the central casing portion 4 and form withthe same expanding and contracting chambers comuunicating with inlet andoutlet means 4a, 4b, and also bounded by the inner faces of cover plates3 and 4. The machine is preferably used as a combustion engine, suitableignition means, not shown, being provided, but it is also possible touse the machine as a hydraulic motor or as a pump.

Piston 9 has a central opening 9b through which a portion of shaft 1passes without touching the walls of the opening. Three circular bores 8are formed in piston 9, spaced the same distance from the geometricalcenter 90 of piston 9, and from each other. The center 90 is locatedeccentric to the axis of shaft 1.

A circular member 17 is located in each bore 8, and forms part ofeccentric means which further include a shaft portion 7 whose axis isparallel to the axis of the respective circular member 17, and a supportportion 7a to which a pinion 10 is secured. The three pinions 10 are inmeshing engagement with the stationary gear 12. The lines connecting theaxes of each member 17 with the axis of the corresponding shaft portion7, are parallel to each other when the pinions 10 mesh with spur gear12. The transmission ratio between pinions 10 and gear 12 is one tothree.

The eccentric means 7, 17 support the rotary piston 9 on the flange ofshaft 1 in such a manner that the corners of piston 9 move along anepitrochoid line exactly corresponding to the shape of the inner annularguide face 4a of the casing portion 4. The composite motion of piston 9is transmitted by the eccentric means 7, 17 to the star-shaped flange 2and to shaft 1 which serves as output shaft if the machine is operatedas a motor. Piston 9 is also supported by the three pinions 10 .at threeperipheral points of gear 12.

Due to the fact that the rotary piston is supported by three angularlyspaced elements, binding, jamming, or fluttering of piston 9 isprevented.

If play develops between the teeth of pinions 10 and gear 12, it iseliminated by turning gear 12 a corresponding small angle afterloosening screws 14, whereupon the gear is again secured to the casing.By similar adjustment, the position of the rotary piston 9 can be foundin which the sealing elements, not shown, provided at the corners of thepiston, are disposed so that no pressure is exerted on the same duringrotation of the piston.

The embodiment of FIGS. 4 to 7 corresponds to the embodiment of FIGS. 1to 3 as far as the general construction of the machine is concerned. Asbest seen in FIG. 4, piston 9 has at the ends thereof a pair of recesses9d connected by a central opening 9e. Gear 12 and flange 2 arerespectively located in the two recesses 9a, and a portion of shaft 1passes through the central opening 9e. The eccentric circular members 17are located in bores 8 of the central wall of piston 9 between shaftportions 7 and supporting port-ions 7a for pinions 10. As in theembodiment of FIGS. 1 to v3, flange 2 and gear 12 are located withinpiston 9, but in contrast to the embodiment of FIGS. 1 to 3, gear 12 andflange 2 are not located adjacent each other so that the piston issupported by pinions 10 and shaft portions 7 on gear 12 and flange 2symmetrically in relation to the central wall of piston 9.

The embodiment illustrated in FIGS. 8 to 10 provides piston 9 in thechamber formed by central casing portion 4, and cover plates 3 and 11,but the other parts of the machine are located in a second casing 19which is secured to the first casing housing the rotary piston 9. Piston9 has a central fluted bore into which a corresponding shaft portion ofa member 15 projects, so that piston 9 and member 15 together form arotor performing a composite rotary motion as the corners of piston 9move along the epitrochoid guide face of easing portion 4. Since theshaft portion of member 15 revolves about a small circle, cover wall 3has a corresponding opening 3a. Shaft 1 is mounted for turning movementin a bearing 5a in gear 12 which is mounted on casing 19 by means ofscrews 14 passing through slots 13, see FIG. 9, in order to permitadjustment of gear 12. Shaft 1 terminates in flange 2 which has threebearing bores turnably supporting shaft portions 7 of eccentric meanswhich include circular eccentric members 17 mounted in correspondingbores 8 of member 15, and support portions 7a on which pinions 10 aremounted in positions meshing with spur gear 12. Due to the fact thatcover plate 3 separates the combustion chamber formed between the innerguide face of easing portion 4 and rotary piston 9 from the torquetransmitting and supporting means located in casing 19, the same areshielded from the heat developed in the casing 3, 4, 11.

The eccentric means described with reference to the embodiments of FIGS.1 to 10, may be modified as shown in FIGS. 11 and 12. Instead ofproviding circular eccentric members 17 of greater diameter than shaftportions 7, crank shafts 16 may be used, each of which includes a shaftportion 7 mounted in the flange 2, a support portion Tr: to which apinion 10 is secured, and a crank portion 7" located in a bore of rotarypiston 9 as described with reference to FIGS. 1 to 7, or in member 15 asdescribed with reference to FIGS. 8 to 10.

In all embodiments of the invention, the shaft rotates at the samerotary speed as the rotary piston 9, as compared with prior artconstructions in which the shaft is driven at three times the rotaryspeed of the piston, unless a reduction gearing is provided. The meshingengagement between the stationary gear 12 and the three pinions 10 isparticularly smooth, and advantageous as far as the exact guidance ofthe rotary piston 9 is concerned. Due to the precise control by pinions10 rolling on gear 12, and by the eccentric means 7, 17, fluttering ofpiston 9, and intermittent shocks on the corner portions of piston 9,and the corresponding sealing means are avoided. The transmission ratiobetween the pinions and the stationary gear may be selected as desired,and more than three eccentric means may be used for connecting the rotorwith the flange of the shaft. The rotor of the machine may consist ofthe rotary piston 9, as described with reference to the first twoembodiments, or may include member and the rotary piston, as describedwith reference to the embodiment of FIG. 8.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofrotary piston machines diifering from the types described above.

While the invention has been illustrated and described as embodied in arotary piston combustion engine including a plurality of eccentric meansfor connecting the rotor of the machine with the output shaft, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotor including arotary piston means in said casing means having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a flange on said shaft; and a plurality ofeccentric means angularly spaced about said axis, each of said eccentricmeans being mounted in said flange and in said rotor, respectively, forturning movement about parallel axes so as to transmit a torque betweensaid rotor and said rotary means.

2. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotor including arotary piston means in said casing means having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a star-shaped flange on said shaft; and aplurality of eccentric means angularly spaced about said axis, each ofsaid eccentric means being mounted in said flange and in said rotor,respectively, for turning movement about parallel axes so as to transmita torque between said rotor and said rotary means.

3. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotor including arotary piston means in said casing means having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a flange on said shaft; and a plurality ofeccentric means angularly spaced about said axis, each of said eccentricmeans including a shaft portion mounted in said flange and a circularmember mounted in said rotor, respectively, for turning movement aboutparallel axes so as to transmit a torque between said rotor and saidrotary means.

4. A rotary piston machinecomprising, in combination, casing meanshaving an inner non-circular. annular guide face; a rotor including arotary piston means in said casing means having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a flange on said shaft; and a plurality of crankshafts angularly spaced about said axis and having journal portionsmounted in said flange and in said rotor, respectively, for turningmovement about parallel axes so as to transmit a torque between saidrotor and said rotary means.

5. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotor including arotary piston means in said casing means having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a flange on said shaft; a plurality of eccentricmeans angularly spaced about said axis, each of said eccentric meansbeing mounted in said flange and in said rotor, respectively, forturning movement about parallel axes so as to transmit a torque betweensaid rotor and said rotary means; a piston secured to each of saideccentric means for turning movement therewith; and a stationary gearmounted on said casing means coaxial with said axis and meshing withsaid pinions whereby said rotor is supported.

6. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotary piston meansin said casing means having portions guided on said guide face so thatsaid rotary piston means makes a composite rotary motion, said rotarypiston means having a recess and a central opening; a shaft mounted insaid casing means for rotation about an axis, pas-sing through saidcentral opening, and having a flange located in said recess; astationary gear located in said recess secured to said casing means andhaving an opening into which said shaft projects, and a bearing forsupporting said shaft, said gear being located adjacent said flange; aplurality of eccentric means angularly spaced about said axis, each ofsaid eccentric means including a circular member mounted for turningmovement in said rotary piston means, a shaft portion mounted in saidflange for turning movement about an axis eccentric to the center ofsaid circular member, and a support portion; and a plurality of pinionsrespectively secured to said support portions and meshing with said gearwhereby said rotary piston means is supported and a torque istransmitted between said rotary piston means and said shaft.

7. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotary piston meansin said casing means having portions guided on said guide face so thatsaid rotary piston means makes a composite rotary motion, said rotarypiston means having recesses at the ends thereof and a central openingconnecting said recesses; a shaft mounted in said casing means forrotation about an axis, passing through said recesses and said centralopening, said shaft having a flange located in one of said recesses; astationary gear secured to said casing means and located in the otherrecess, said gear having an opening into which said shaft projects, anda bearing for supporting said shaft; a plurality of eccentric meansangularly spaced about said axis, each of -said eccentric meansincluding a circular member mounted for turning movement in said rotarypiston means between said recesses, a shaft portion mounted in saidflange for turning movement about an axis eccentric to the center ofsaid circular member, and a support portion located in said otherrecess; and a plurality of pinions respectively secured to said supportportions and meshing with said gear whereby said rotary piston means issupported and a torque is transmitted between said rotary piston meansand said shaft.

8. A rotary piston machine comprising, in combination, casing meansincluding a first casing having an inner non-circular annular guideface, and a second casing secured to said first casing; a rotary pistonmeans in said first casing having portions guided on said guide face sothat said rotary piston means makes a composite rotary motion; a rotarymember locatedin said second casing; means connecting said rotary memberwith said piston means so that said rotary member participates in saidcomposite motion; a stationary gear secured to said second casing andhaving a central opening and a bearing surrounding said central opening;a shaft partly located in said center opening and supported on saidbearing, said shaft having a flange located between said gear and saidmember in said second casing; a plurality of eccentric means angularlyspaced about said shaft, each of said eccentric means including acircular member mounted for turning movement in said member, a shaftportion mounted in said flange for turning movement about an axiseccentric to the center of said circular member, and a support portion;and a plurality of pinions respectively secured to said support portionsand meshing with said gear whereby said rotary piston means is supportedand a torque is transmitted between said rotary piston means and saidshaft.

9. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotary piston meansin said casing means having portions guided on said guide face so thatsaid rotary piston means makes a composite rotary motion, said rotarypiston means having a recess and a central opening; a shaft mounted insaid casing means for rotation about an axis, passing through saidcentral. opening, and having a flange located in said recess; astationary gear located in said recess and having an opening into whichsaid shaft projects, and a bearing for supporting said shaft, said gearbeing located adjacent said flange; adjustable means for mounting saidstationary gear on said casing means; a plurality of eccentric meansangular-1y spaced about said axis, each of said eccentric meansincluding a circular member mounted for turning movement in said rotarypiston means, a shaft portion mounted in said flange for turningmovement about an axis eccentric to the center of said circular member,and a support portion; and a plurality of pinions respectively securedto said support portions and meshing with said gear whereby said rotarypiston means is supported and a torque is transmitted between saidrotary piston means and said shaft.

10. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotary piston meansin said casing means having portions guided on said guide face so thatsaid rotary piston means makes a composite rotary motion, said rotarypiston means having recesses at the ends thereof and a central openingconnecting said recesses; a shaft mounted in said casing means forrotation about an axis, passing through said recesses and said centralopening, said shaft having a flange located in one of said recesses; astationary gear located in the other recess, said gear having an openinginto which said shaft projects, and a bearing for supporting said shaft;adjustment means for mounting said stationary gear on said casing means;a plurality of eccentric means angularly spaced about said axis, each ofsaid eccentric means including a circular member mounted for turningmovement in said rotary piston means between said recesses, a shaftportion mounted in said flange for turning movement about an axiseccentric to the center of said circular member, and a support portionlocated in said other recess; and a plurality of pinions respectivelysecured to said support portions and meshing with said gear whereby saidrotary piston means is supported and a torque is transmitted betweensaid rotary piston means and said shaft.

11. A rotary piston machine comprising, in combination, casing meansincluding a first casing having an inner non-circular annular guideface, and a second casing secured to said first casing; a rotary pistonmeans in said first casing having portions guided on said guide .face sothat said rotary piston means makes a composite rotary motion; a rotarymember located in said second casing; means connecting said rotarymember with said piston means so that said rotary member participates insaid composite motion; a stationary gear having a central opening and abearmg surrounding said central opening; adjustable means for mountingsaid stationary gear on said casing means; a shaft partly located insaid center opening and supported on said bearing, said shaft having aflange located between said gear and said member in said second casing;a plurality of eccentric means angularly spaced about said shaft, eachof said eccentric means including a circular member mounted for turningmovement in said member, a shaft portion mounted in said flange forturning movement about an axis eccentric to the center of said circularmember, and a support portion; and a plurality of p1nions respectivelysecured to said support portions and meshing with said gear whereby saidrotary piston means is supported and a torque is transmitted betweensaid rotary piston means and said shaft.

12. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotor including arotary piston means in said casing means having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a flange on said shaft; a plurality of eccentricmeans angularly spaced about said axis, each of said eccentric meansbeing mounted in said flange and in said motor, respectively, forturning movement about parallel axes so as to transmit a torque betweensaid rotor and said rotary means; a pinion secured to each of saideccentric means for turning movement therewith; a stationary gearcoaxial with said axis and meshing with said pinion; and adjustablemounting means for mounting said stationary gear on said casing meanswhereby said motor is supported.

13. A rotary piston machine comprising, in combination, casing meanshaving an inner non-circular annular guide face; a rotor including arotary piston means in said casingmeans having portions guided on saidguide face so that said rotor makes a composite rotary motion; rotarymeans mounted in said casing means for rotation about an axis andincluding a shaft and a flange on said shaft; a plurality of eccentricmeans angularly spaced about said axis, each of said eccentric meansbeing mounted in said flange and in said rotor, respectively, forturning movement about parallel axes so as to transmit a torque betweensaid rotor and said rotary means; a pinion secured to each of saideccentric means for turning movement therewith; a stationary gearcoaxial with said axis and meshing with said pinion; and adjustablemounting means for mounting said stationary gear on said casing meanswhereby said rotor is supported, said adjustable mounting meansincluding threaded means for securing said gear to said casing means inadjusted positions.

14. A machine as set forth in claim 13 wherein said gear has a flangewith a curved slot, and said threaded means include a screw passingthrough said slot and threaded into said casing means.

References Cited UNITED STATES PATENTS 3,260,135 7/1966 Eisenhardt74--802 RALPH D. BLAKESLEE, Primary Examiner.

1. A ROTARY PISTON MACHINE COMPRISING, IN COMBINATION CASING MEANSHAVING AN INNER NON-CIRCULAR ANNULAR GUIDE FACE; A ROTOR INCLUDING AROTARY PISTON MEANS IN SAID CASING MEAN HAVING PORTIONS GUIDED ON SAIDGUIDE FACE SO THAT SAID ROTOR MAKES A COMPOSITE ROTARY MOTION; ROTARYMEANS MOUNTED IN SAID CASING MEANS FOR ROTATION ABOUT AN AXIS ANDINCLUDING A SHAFT AND A FLANGE ON SAID SHAFT; AND A PLURALITY OFECCENTRIC MEANS ANGULARLY SPACED ABOUT SAID AXIS, EACH OF SAID ECCENTRICMEANS BEING MOUNTED IN SAID FLANGE AND IN SAID ROTOR, RESPECTIVELY, FORTURNING MOVEMENT ABOUT PARALLEL AXES SO AS TO TRANSMIT A TORQUE BETWEENSAID ROTOR AND SAID ROTARY MEANS.